A synthetic zeolite is crystalline aluminosilicate, and has uniform pores that are attributed to a crystal structure thereof and has an angstrom size. Taking advantage of such a feature, the synthetic zeolite is industrially used as a molecular sieving adsorbent that adsorbs only a molecule having a specific size, an adsorption separating agent that adsorbs a molecule having strong affinity, or a catalytic base. PAU is a name that represents a skeleton structure species given to a paulingite zeolite, and a zeolite having the same structure is ECR-18. The PAU zeolite is used as, for instance, an olefin synthesizing catalyst in the petrochemical industry (see Patent Document 1).
Conventionally, the PAU zeolite has been produced only by a method of using it as an organic structure defining agent (hereinafter abbreviated to “OSDA”) such as a tetraethylammonium ion (see Non-patent Documents 1 to 3). For this reason, to obtain the PAU zeolite, the use of the OSDA has been considered to be essential. Further, since the synthesized PAU zeolite contains the OSDA, it has been considered that it is inevitable to fire the PAU zeolite to remove the OSDA before the PAU zeolite is used.
A method of synthesizing the PAU zeolite is described, for instance, in Non-document Documents 1 to 3 described above. A typical method is a method of using the tetraethylammonium ion as the OSDA under the coexistence of a sodium ion and a potassium ion. However, the OSDA is expensive, and what is more, most of the PAU in a mother liquid after PAU zeolite crystallization is terminated is sometimes decomposed. Further, since these OSDAs are incorporated into a crystal of a zeolite to be created, it is necessary to fire the zeolite to remove the OSDAs when the zeolite is used as the adsorbent or the catalyst. In that case, exhaust gases are responsible for environmental pollution, and further, many chemicals are required for detoxification treatment of a synthetic mother liquid containing decomposition products of the OSDA. In this way, the method of synthesizing the PAU zeolite using the OSDA is not only an expensive method but also a production method having a great environmental load. As such, there is a need for a production method of using no OSDA and realization of the PAU zeolite that is obtained by such a production method and essentially contains no organic substances.    Patent Document 1: Japanese Unexamined Patent Application, Publication No. 2006-182792    Non-patent Document 1: Microporous and Mesoporous Materials, 28 (1999), 233 to 239    Non-patent Document 2: Microporous and Mesoporous Materials, 83 (2005), 319 to 325    Non-patent Document 3: Glass Physics and Chemistry, 37 (2011), 72 to 77